Protection tape typically does not do a ton for protecting frames from court rash. All the tapes i have encountered become demolished after one hard court dig. I rush the net fairly often, and as a result, i dig for low volleys quite often. I also feel that the tape gives a VERY SLIGHT resistance to string movement, which muddies up the feel of the frame, it also adds VERY VERY slight balance/weight changes to a frame. I just don't like using it, personally.

Change it as often as you need to, people have different needs, some people use tape for cosmetic reasons, others use it because they have paper-thin bumper guards (Prince TT series, anyone?), etc.

Tape the bumper guard and if you are truly anal, you can tape any areas that you are concerned with getting court rash on.

I have always used the babolat head tape on all of my racquets, and it keeps the head and the bumper guard looking like new. Obviously it won't prevent all damage, especially if you dig out a lot of low volleys and are constantly scraping the frame, but it will help preserve the bumper guard. I buy and sell racquets all the time, and I always get top dollar for used racquest because the frames and bumper guards for the most part are clean. I have never noticed any difference in play with the tape on vs. tape off. I change the tape at ecery stringing, or if it is banged up.